SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfdf4b2a97612b36f4c028937e459c3c413aa40038edbee506361549a457c4b5' 
  AND token = 'eVpbVicUrhaVJcOJDsyYmCme/pTHBq0TZHEHYsSaMiw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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