SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2c4974748176fc19fef8be983e4affb9aa0b39b6d8e7020d8d2a0378fc16865' 
  AND token = 'VNblYDESJPw2Adt8knvJ7edIhJ+MDwEMoTrSqUSjAz0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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