SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aeb4c798ff04094d09ea2e9f2af782b4e878cb5d5c3816e54a9ae1be59f9b464' 
  AND token = 'S/iz51SeikKKIG30k4lB+Yo9NN7jeujr1PovLiZ3NmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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