SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcac65bb548223cb953733c5d740423bccdd3acc5b69e30667b684fb83b48c04' 
  AND token = 'e7Vq+xmbwQVMxB3NxB/tUCMiLKnebAqf4Ya8exPvkio=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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