SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc6c4908097602c412db29dc8edfb1dac3a005212fb0dbafbf5475e8d3e74467' 
  AND token = 'sw0JoStVNGSVjiK5IQfgAlOMj+opAShYbWw6/lBCIxo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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