SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '509351bfda750ad393b6d1c9d387cf1b169b731c862a109458370298c5846c74' 
  AND token = 'x2QPBE2sGaBbG/PW2ia7VxK4/wL/tofjAfrErvxaHzg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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