SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ec2980609af15a11cefb5abf52e86d91111f5af95a114589ecd0229c8e4b3126' 
  AND token = '5zsD3WGvSb5LZIfdN1fvT3IYkrbxro2g53BBJ/cZgPk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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