SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bf1fcb73535b2d2a4161db813c61657d43823f3f31cac25e18d9aa5e0d727e2' 
  AND token = '0pJrLmS6gaVtYS+kg8f6GZLOspC2OrwVBoP96i4lIPU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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