SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7e3f662546e5ee0ebcc3c7aa03e428d6195268a9445cb697bb0145c4a2db8aa' 
  AND token = 'r/zSHlsb3y+QsITa/vMOL3ZZnj4lG1V3cuQiUI5Qk3k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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