SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52c0355f151bc8036ea4a43d362478ac10e4cf906867de25ac39958b3cf04a75' 
  AND token = 'MStOiYYVhGjK4JyF2AC8SU+qp7kwnp70XXDx+yUhQXc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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