SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0371245fb534ffd8125d1d2f479275c375b2f4c973904c84b7f8e2384269ede1' 
  AND token = 'RLgv6XjdI2nHxkRaG4HJ/1xdz+lTezxKwC5RmLXSyAc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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