SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9392af9428166eb38dcde22625325661392b73bf7771a99c40cdb5767969bcf0' 
  AND token = '3ZUbf0Ovzux5zdm5L1Ck4xouBWTKiL2Hzzc+Bvciiac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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