SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9549cc5ca373cb867c2a858a1a2122256b7ab98914c3f89322d3a4ec8827131d' 
  AND token = '3qMJUoxwXy/Q3EHGlzKhZMs5gekINYU24oRV75XKCdQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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