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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd9f2958ab7d8b50a6e0cb49977714d36e77ed8882c1ee8e74ad2f5b015531cc' 
  AND token = 'CjexA1+qarPvdTfY+6EiT9sV1/qDRc72cl1Qd3VsJlA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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