SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4542ce9e69f7a21ca63bd8382eaecaa4b77ac0ddd1bffb690f547ebabc74f14c' 
  AND token = 'hJyQDhofTgGffOf+oApBzV2e5uQCGUvT/sXwfdjIOqI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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