SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7dc5a572129d6c8fa2504f2fcc7d613d1213383b747409943687f63e31552d31' 
  AND token = 'doUr7y2VZNKTLlyQUm9CuyggJUIq+UzVV3B8UbrS8uQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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