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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15d9ccd16fc0ec19489deff5adde3bef8549bf7dad1a2e5a3a51fab2de948bfc' 
  AND token = 'kJlmfWHo+H7e5ORfaVMPlXheXL+4WF0IJOGIbTR4nQk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}