SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2140225661523a8008aa1fa2287507bd128f7761e82bf389bccad25a9cdd9121' 
  AND token = '8Btg6+8K7pcrjRGHxpW44cCTqIDtfse66NDESxY2DI0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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