SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'b8e66f4a259f095c66ddd3bba84fb8292da5433ee6a52fc9942f746c120819b1' 
  AND token = 'MaZehgcjthsCCwGg+3hzhphS4VTLXhdFEP2BKwfX+WQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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