SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a521bcbf58a81426aee4f19cff95403306c24e72556487c4abfe58cd2ef7ab1b' 
  AND token = 'DjmnNyjudmuRzYfSh0E+vn+3oYdxDK+qGRYc/oUJdbE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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