SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e0757c6435d76500af00756c6740a0342e5d54d44788c5b18e542ed17b5f056' 
  AND token = 'bNlGx0vbttR1PzxnEHO5Zo3TWr10KHtRAGqHYFC0xwI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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