SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'a8794b9dba75ef93fd26ab7983973cba01f1b5c7c05a52458635d18b6777db7a' 
  AND token = 'vyD6FpdVwfhxe8IrvyrZtdiDwrZRqchu8g2/FN3gKnE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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