SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84b0ce8198665fab757d7cd52856b10e16436e50975cb03ffc10f9ad6776aefd' 
  AND token = 'G9LhvAD+h5l/1HfgRlHDVG6cbvwAr/stHdKrgwYPm58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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