SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff11b31219755ffb5300dd14d57487a16f62db2de9e20b011318db99c151982c' 
  AND token = 'NBkjXBqBnxNY3UmgSZrkyGsspBpvHW1UFiLGJoZja7Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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