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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50f17509fba5ff0bee1dcf4ab941d2f95ec7f7d52932bd32904c14813a97b9e6' 
  AND token = 'DT/yF4pzoGc1rQW2NZ9HgkVRKcR8Eb5T0SEu8C6C5AE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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