SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ed7794bfb256315b59dbe54605beb938919fa1384efd603d5ebd91113652d875' 
  AND token = 'fhXlIUE12ktLsyrSTwY9tCg6vK8epMCrgQMwRwlr+9s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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