SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91553b2f44729aa3118cf9e980d3990109b38b1b0723935a29ea9705dd7b25ec' 
  AND token = 'KH1NNR6gVvYv+K3oCMWc/LkWPwEYxkrywmlLL3mzrhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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