SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7fc39104007e141f7ec26ecf228db27a836c509e74ed92fb8b7b24f7a0dd9c24' 
  AND token = 'EytKSaflQcjdpQ8RaBBveVxLESZTrM+/5AE/CX7ffAk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}