SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5586d3a006f46e4943e8992aa8a9115978338c2a775d0b17f198645498144ec1' 
  AND token = 'n/tcfSKYuz5iwK8M9OEZtkOshWbvVfW9dsrAEdbE7ds=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00078

JSON explain

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