SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50359896e629ca8af5c6d149960f772aa91fcb9030ef774ad412e9087709c7ff' 
  AND token = 'adpgz0l9WcknIZazlLPcZwOfzWyvsJJsz4RvcJXLzUc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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