SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '423672478690a8bebcb85d2b0e947e9e26a9b426341daceba090debf26b022d0' 
  AND token = 'ZfgJoNDW9JGSDD9nC7rFy+y8I2+hQ4C2EVJUu/CYYKs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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