SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e331ebca66fe20fb756fa0a708b136e94b4c08c90701e3f1086d808bba08672b' 
  AND token = 'nxj1bv8Z5d018Jm+5BUWi0uDYoE1X4VderVVTq5v5DQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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