SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e3cb9e367a4252b61fbdfd7bd6ff0edf9f39a48161409ec732729e296b8cdae' 
  AND token = '8QqV88G1qMeahUNShnlr5TPDcAeIM+0QxL2zSbLQk44=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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