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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8c916877e9a3b86732bfa62ab2aa658c56acaf62b679d2e03a4a9993b9bfdf5' 
  AND token = 'ji7YnJx1cu+HnDIXBV66DbjSDiPGyPnbUVBGM2KD4KA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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