SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ce75d87ff16810af4f89d7dc29186ab90ee94e78cf15df6ea5221dd7c32c09c6' 
  AND token = '3VC6chfioazKd4dKbbwMLL/oTFpBhT5ouIiWjbhGXgY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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