SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75a9a00e54685a02ec1cba2bb7303c00b6b1a8e224b3686615403f2afcf3d2a3' 
  AND token = 'FcV2sWa6B+eyP2c+RSp6Z4LDIFcFiYsBxCIWecsUVLA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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