SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3273698ac9daf65b3584178675d87e7a60dfb7f9d65ae1ca0fc262e9bc1fc89a' 
  AND token = 'GCtxLxiwcpmN0ZqvnwkUcaNE+0vqapmKZILVXDMPJNE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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