SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d684d7415608d0424b3f782a1596cae1027b5c77399b18048ccd0e2b9c39fda' 
  AND token = 'FPETkiidQMz1WWiLOB1xEt7XKpUqbzAHlVyI5Kh8BYE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}