SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df78fbb9ea016d0b5b09d36217b3cd85d652051743b21c46b0f84a37cdee4329' 
  AND token = 'OrVxR/Nt8kGW4Bn+VgZkFlF1Fu1CW+MmIkAFzUT/P+E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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