SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54d5435a58e49f52b95dea7694721c389fb589f33984691f50e07c281a842bcb' 
  AND token = 'f/aGZN9UUssDzlsvjFFFOZDTjrVxpIMlymH7/7xg3ik=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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