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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc21e97ff3c89628a9243cc3733524dd5c14ad7610a941a85dea2159f09da90c' 
  AND token = 'h8gt5BBZZX9YS/RFBuAG0jAE1S3wFjP8Oa0Hg1ClABw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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