SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '241a54b543eba5deb812fc46ea6df7a3e8306cdb67c2e31c72a1d864de35181c' 
  AND token = 'BgtPYu4BcpczYsrvOy0iiS1NzowEzcSzyGoIIIvf9+I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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