SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd81b580efc5d62be69a19ab04b30c55755a09a100dd2fe540696af6bab2f019c' 
  AND token = 'oVf8HZGvCNeQKW8Dgmrdt9IGkGuG2C4rCUT+xFpNeMQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}