SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2876f2d5eb38122f535892a443354f68163f0d43fdf163efb40c12141f225710' 
  AND token = 'GBkvLDJjedZ+YtgaLIBpR5vzAxB5LBWn73KKXxaPr6c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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