SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6354f96dc636f83517945c2fce12c1f15c210114f08a7b126f2784a8e0045c6' 
  AND token = 'pT6FH80hb0iPH7PeyIvdi+bbO8pK7Q3FQupq3xMluFQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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