SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '121da13fcdfd62bceafab0d37fbde5e73c406eb776b79144fedf335f8b06f2d6' 
  AND token = '8zzTkYLCYqdM42msBJg+Q8gTRpFQKkRxi4VDLPXJBZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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