SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2cefe31eb998b403689cea58112e3dbd3411a454c9e4d3fbe1e157a71df3be6' 
  AND token = 'F9xryQiSA/gXuJ9iYfqSMTx6WZWgwUnorWE9HfTWigg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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