SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '526635ccd3584a689aca20cd645aa77a4809eaa20907b72c05e18bcdf429bae2' 
  AND token = 'i71uV4OK7nWNS5u8kHzaYH5dvbe6o+HCWUhmxc+6fCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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