SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5e4f7bff90a3a0ab759e20e7cca38a7ea684df8e6ec2c800408cfa80727a6cf' 
  AND token = '5Q2Qu8BH4wBq5mKGiIjDzZ5RgUnpAQuOvNTjPTsV/F0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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