SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d7abb21464cc0bcabcf7cdd5f087e088f11923572f20ebc700842fb41ea4992' 
  AND token = 'U8WrdXLBuM8IjMjwMcG0pzsHoYRS8BlSVdTFjymtW+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}