SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2352efbcb457a8a2be7700a1c8543ca0e754b7146b012026022fd153e122b5b' 
  AND token = 'fkMMYJqH93P1j0vhXovdozOLDGSIaGHsgaaNs+D0X80=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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