SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '790ed34ed802093f74be282befc9124bb91fe3abf17549185567b62e91d25ea0' 
  AND token = 'FX2zsmzdom0F27T3Kh5T7qWSRaPE/NVNvebSTsQ8quw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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