SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3bdfed6ca1bd48bbc3747a7128f71c9b98da01b9b4f60e11c9116f5b339b35c2' 
  AND token = '0zK7DAikem1UMLioKoeYV55CJgU4mEjBq0JZphDKbt8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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