SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53ff3d1efb7e59aea7f6ca4c499e2bff50be1cf01978930b85e9a20d0e4a73ab' 
  AND token = 'QgiJA9Ll1BW3vHpT4wqG+6DmlC6ylSR4XEdwKmz2pI8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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