SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '923b38fd62a838711d6b2c3c24509ebeeb5142214c820411470e113a088e02bd' 
  AND token = 'c1bfUlASp3Lv3iQjmXRLDqSlQFhBD/9xsleP8NyT15A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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