SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b981d651a5fbed507912740adf17873709010f9f9c25c3d4dde18780d77a115' 
  AND token = '7eLyniHpIuYE3MPSe0Xm/9qRAugvgPbmPW7Hq3dosSA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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