SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12b8a1f0ec47bc70853d3b6710fde44bf61d49b2d6da3939cd324040c811fcc7' 
  AND token = 'GqIMCuyuekBQPyJtrgl53F6ZixVP+jRCVubRFW/4Kng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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