SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b345723ba1ea8bd3eaa8da36e816f9b6df56895db8945f68e3ad37e1142833db' 
  AND token = 'rhPvKUB1UcY9l9QFKCBJfvSrLlj/OX++UTbx4cVHpkE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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