SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '297fea454897424a851e6c8441dc16cedfe5b0d815c92aa97654cb5e96508000' 
  AND token = '1hgCIgjfyfpvu3EocpkI+gJ+jRJG1tdOImBanjIyv9Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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