SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcf9ded54503bb682c689ea0a5c4b89aa0da16e1cefb64ee4aff3e1baa1d8edc' 
  AND token = 'agMhnEn0HNeTTuA7S1aw85BGiyRACPb3SGrlv1JQ3T4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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