SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b62d8b00eca2cf7a3200d843c320b4874516c0e9f0f43b0c6229308b8d447a66' 
  AND token = 'RwN19kicGbjc4eBLWx4HqSRTtTppQVddZnSb7vpkJ2M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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