SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd88bd65cf42d13de77e9c87234b523ee62ada432511ded6eb8c48b01dfb9298a' 
  AND token = 'mfoPHxmtGVcnbnhLoFmmfS6xbxVdcWVQDPCsMkPbYwo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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