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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7278709386c5a0967b116a54e6bc282957c38871a3fa78f96a5a608b94da69b3' 
  AND token = 'EW0r/opyWkm2wQkNReoPXzM1vweTx6h5HNFc88saxUI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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